Abstract: A method is provided for determining in real time the course of proteolytic, e.g., thrombin activity, in a sample of clotting blood or plasma. By frequent mixing of a sample, clot formation may be controlled in a dense manner such that the majority of the sample remains fluid. This will inhibit cell precipitation and allow for informative monitoring as signal substrate is added.

Abstract: A method is provided for determining in real time the course of thrombin activity in a sample of clotting blood or plasma as it appears in and disappears from the sample which comprises adding a signal substrate to said sample, said signal substrate causing a detectable signal related to the amount of conversion product formed upon reaction by the generated proteolytic activity, monitoring the signal development in time in said sample to provide a curve, and mixing said sample frequently so that clot formation occurs in a dense manner such that the majority of the sample remains fluid and that cell precipitation is inhibited, wherein said monitoring and mixing steps are repeated and performed in an alternate way.